rx7speed

dont really have much to do anymore and have a friend with a car we are dinking around with

between the both of us he thinks we might be able to make a intake with tuned runners so we would be able to make a much flatter torque curve

just trying to ask you guys if you think it would be worth it
and if you have an idea or two? or has anyone tried to build one before?


I know the rx-7 as well as a few other cars have designs that use one and this is not to be some huge complex setup or anything though

bjankuski

ZR-1

SpeedCat86

Are you talking about runners that you could adjust for tuning, or 'variable' runners that would go from long for low rpm torque to short for high rpm hp?

a manually adjustable one shouldn't be two hard, just use telescoping tubing, and clamp it.

most variable runners use two sets of runners with a buterfly valve to switch paths.

The new BMW 7-series V8 uses a series of rotating disks to vary the runners from like 4 inches to 12 inches in length. I think Car&Driver or Automobile magazine had a diagram of it a couple of months back.

BTW: what engine are you trying this on? I may have to put some thought in to this.....

rx7speed

first car to get it will be my rx-7

and then depending on cost and how much of a pain it is I might try to make one for a tpi setup.
from there dont know
just again depends on how much work it is and if itends up being worth it

but the ones I am refering to at low rpms you will have a long runner then at higher rpms move to a shorter runner

just need to figure out how I want to get the whole setup to switch between the two then comes all the fun math to figure out how large the runners should be and how long and all that fun stuff

PETE

iTrader: (1)

if you could find a way to time the thing and balance it,i have an idea.you'll need a 350 block and crank.you'll need four 5.7 rods and four 6.0 rods,you'll need a pair of l98 aluminum heads(easy to mod).you'll need eight 2.02 valves and eight 1.60's as well as eight 1.94's and 1.5's.you'll also need tubing or sheetmetal to construct an intake.well here it goes being that you are talking about variable runner length why not go one step further?
if you have 4 cylinders with a short rod to stroke ratio and large valves with the cylinder heads hogged out for volume not velocity and a small runner intake setup those four cylinders should be able to produce good hp numbers.the other four cylinders get the longer rods,smaller valves,smaller intake runner and an ltr setup it should make good tq numbers.i know that there will be variances like piston height,weight,(plays havoc on balancing).my thought would be that the self contained 8 cylinder would theoretically act like to four cylinders one give you the tq to put the vehicle into motion the other making hp to keep it moving.another way would be to have a billet crank ground with offseting strokes on the opposing journals(but that could be very expensive).just an idea spawned from boredom.




As my friend once told me.

"OPPURTUNITY IS MISSED BY MOST PEOPLE BECAUSE IT COMES DRESSED IN OVERALLS AND LOOKS LIKE WORK":lala:

rx7speed

another problem

first I dont have a v8

second well hell I dont even have a v type motor

and last I forgot I dont have pistons

but also doing that setup might play havoc on the induction pulse that each cyl will create
not sure but there might be that chance

and also too much work as you said to balance the motor as it is

just need to somehow figure out to get the runners to work so I can have two of them and then have them switch between the two

I plan on doing this to my rx7 first and then after that if it works out maybe try to get one for a TPI car if I can get someone to work with me on it

LottaBallsCamaro

Use a vacuum activated butterfly. Higher RPM=Higher vacuum.

rx7speed

higher rpms does equal higher vac
but so would the car being at an idle
or cruising on the freeway

there would be too much that could change the open point


I was thinking of getting a rpm switch that would open some sort of valve be it a butterfly or a rotating sleeve(which would be better prolly being it would allow for smoother air flow

the other idea was to get something that would act as telescoping tubing and have some sort of pully system that would adjust it on the fly though that would be a pain in the *** to do
would have issues with getting it to seal I am guessing, also how would I get the whole thing to move to begin with.
this would be the best way though b/c at this point the rpm range for peak torque would be through a very wide range since the intake would be growing shorter with every rpm.


what would be a good thing to make the intake out of


and how could I get all the little holes I would need for the shaft that holds the butterfly valve or rotating sleave to seal. this way it will still rotate but not let enough air into the intake from outside to throw my a/f off


come on any other ideas out there

if nothing else at least keep this at the top
cause if I cna get it to work for my rx-7 I will go for trying to make a v-8 one if I can see a good market for it

camaro6spd

our 97 Ford Contour has something like this....is is a V6 but the intake splits into two sides and has runners feeding each of the cylders, one loger runner running from one side of the "V" to the other and one short runner on the sameside of the"V" as the cyl. I will get a picture. Dunno if they have somesort of valve in them.

Swapmaster

I have torn down several Ford motors that use a split port
intake and it is a cool idea. They are vaccum operated, like
the vaccum secondaries on a carburator. The SHO car also
also uses a split port manifold. When you drive a split port car
you can feel the "secondaries" open up under hard acceleration.

Swapmaster

Yea, just went out and looked at a SHO car intake and each
cylinder has a 12" runner and a 5" runner. The 5" runners are
blocked by butterfly valves which are vaccum operated.

Ford has been using split ports since 89.

rx7speed

send a pic please if you could


also do you have any idea what would be something I could make the whole intake out of

Swapmaster

Are you going to use this on a rotary or a V8?

This will be very complicated to make on a V8, the rotary would
be alot easier.

Swapmaster

Come to think of it, I don't know a damn thing about a rotary
engine. Does it even need any kind of a tuned runner?
It kind of has a constant draw on the carb don't it?

You can only truly tune a port if the air flow stops and starts.

88 350 tpi formula

iTrader: (9)

the 4.3 blazers use this set up. it is all done inside the intake 94? or so are the years

camaro6spd

i'll snap a pic in a hour or so

Swapmaster

I pulled a 4.3 vortec apart the other day and you are right.
They use an electric diverter valve to dump air straight into
to lower intake bypassing the runners in the upper intake.

Swapmaster

I will take the camera to work tomorrow and get pics of the SHO
car intake and the 4.3 vortec intake. I will get the pics up this
week end. I noticed on the SHO intake the short runners were
quite a bit larger diameter then the long ones, stands to reason.

I hate to say it but the SHO is a ***** engine made by Yamaha
but kept up with the Mustang GT's in it's day. Not bad for a 4 door
front wheel drive car.

Bird_of_Prey

umm.. dosn't that new vette by lingfelter.. or however you spell his name, have that? two runners to each intake one short and one long, operated by a vaccume?
pretty sure i saw that.. looked like a SWEET tpi system..

SpeedCat86

Okay, Here's my Idea, based loosely on the BMW 7 Series
The Intake consists of two cans mounted one inside the other. The air enters the inner can, and exits through a port in the side. The air travels from that port, around the outer can, untill it reaches the intake port on the head. The runner length can be adjusted by rotating the inner can, moving the port relative to the exit of the manifold. the airf path is shown by the arrows in the drawings. The red arrow represents the Short runner, the blue arrow, the long runner. The rotation of the inner cylinder would be controlled by a stepper motor, or Servo, attatched to the Throtttle position sensor. At Idle, a long runner, torque setup, and at WOT, a short runner, high HP setup.

this picture represents a view through the end of the system, like looking through the throttlebody.

An SHO engine is not a '*****' engine, any more than an RX Rotary, or an Nissan 3.0L TT V-6 (300ZX) These are real performance engines of Japanese origin. A '*****' Engine is a 1.8L VTEC Honda, fitted with only an intake tube and yellow valve covers, that makes a claimed 400hp. ***** means something that thinks it's fast, when it really isn't. I drove one of the early SHO's: That engine will rev like a Black&Decker on amphetamines and a 5-speed car will give most stock Thirdgens a run for the money.

JPrevost

A picture of a supercharged SHO. Notice the 12 runners.

JPrevost

Another picture

91banditt2

iTrader: (1)

do you have any more pics of SHO's?
my lil bro has a 91 SHO that has suprized a few fox bodies and thridgens.
you can check pics of his car at www.streetdawgracing.com just click on the link below.

Swapmaster

Ok, the GM 4.3 has a diverter valve that serves no purpose that
I can tell. It is not a split port intake.

On the SHO intake.

Swapmaster

.

Swapmaster

The last time I looked a ***** was any Asian engine. I first heard
the term back in about 1977 when I was messing with dirt bikes.

I don't believe Honda was making 1.8L V-Tec engines back then,
but I could be wrong, NOT.

Swapmaster

I wouldn't really knock ***** engines though. Why do you think
the SHO ENGINE was developed. Because Ford need a new
hot-rod ENGINE and did not have the brains to develop one
themselves.

If you look at the power levels the ***** engines attain without
comming apart, HP/Liter, it is really incredible.

MikeS

The BMW setup definately looked cool in whatever mag I read about it in. SpeedCat86's idea based on it looks simple and effective. What I really like about that is that it is infinately variable (in between the maximum and minimum lenghts), whereas diverter valve setups only have two options.

JPrevost

I think I know why "*****" engines make that kind of HP/Liter and hold together....it's called build a small engine. With a small engine you have lighter parts (less moving mass).
It's also amazing how they aren't known for their larger displacement engines. They're a small engine, power adder kind of country .
I think it's about time we stop looking only at Japanese technology and start tooting our own horn. Look at the 89 TTA, the GN and the Turbo Omni, amazing engines. How about those drag cars that seem to last forever even though they've got a much heaver rotating mass.
I think everybody has their strong points and to live in the US and boast about foreign imports is like me going to my neighbor and taking money out of his pocket and giving it too somebody in another country. Sorry, I just have that REAL desire to keep my economy headed in the right direction , German cars are the exception (love those Audi and BMWs for daily drivers).
I can't wait until the US gives up the whole SUV fad and the "Big 3" start investing money into smaller more powerful engines.

Swapmaster

Yea buddy !

rx7speed

well nowthis post took off


the only problem I have with the BMW intake is that I can't really move my TB much b/c I have a rod that needs to be able to connect to it and I don't want to start tweaking with that


give me a few days I and I will post what my stock intake looks like and then some ideas as to what I might try to do

TexasB4C

iTrader: (1)

I was thinking you could modify the stock tpi plenum runners and manifold for variable runner lengths.... use a set of runners to cut up (or use aluminum tubing) and drill holes in the bottom of the plenum to run straight down into the intake manifold ( which i see the manifold ports are RIGHT THERE), this will of course eliminate the EGR but who needs that. next use butterfly valves and either a vacuum or throttle cable to open the valves all at the same time, main thing is trying to seal the new runners in place ? either weld them to either the plenum end or the manifold end and bolt them to the other end, sounds easy in theory and after i get the camaro running i plan to get an extra plenum and manifold and see what i can make out of it, and get it Dynoed at my school, UTI, to see the gains,
ill be running this by my instructor tomorrow to see what he says but what do you all think?
i think it would really kick the TPI up a notch

rx7speed

wow this is bringing up the dead
but don't have a thirdgen near my anymore too look at don't really have the tools anymore since my friend moved and don't even have the rx7 anymore to toy with this idea on since it is broke down at my friends house and I'm driving my honda


can still think though and see what I can do with my honda since it is undergoing some work rigght now also

shaggy56

You mentioned something about sealing a telescoping runner. I dont see why you couldnt use a ribbed type rubber (yes i said it). Similar to like what a cv joint has. Still i have no idea how you would get it to telescope.

TexasB4C

iTrader: (1)

no need for it to telescope, just use aluminum pipe or a set of cut up to fit runners it only has to go about 2 to 4 inches from the bottom of the plenum to the manifold... straight down... just have to decide how to bolt it up or weld it on

JPrevost

I think he was revering to "variable" intake runners, not dual runner like you're idea.
I've tooled around in my head the same idea for a while but the work and angle of the short runners wouldn't be optimal to making high RPM power (short runner). So I just gave up and designed my own that is basically a tunnel ram where the long runners come right up out of the port like the "ram port" intakes and the shorts would go straight out... but then where to put the fuel injectors . I won't release my plans because I've spent a ton of hours on it but you get the idea.
Another idea is to have just a resonance chamber/flow equalizing plenum that isn't attached to the throttle body. The older JDM Maxima's have this technology and Ferrari's been using it for what seems like forever. All you'd do is open up the runners in the base and weld on a chamber. This would use the resonance of the shortened runners but the air flow would still come from the long tubes. Proble with this is that the long tubes are rather restrictive for large displacement v8's even in stock form . For that reason I doubt it would make any more power on an air flow limited engine.

Red Devil

Mmmkay... I know someone working on something like that now, similar to the V6 SHO setup not the V8 SHO setup. More than that I'm not talking. Oh, and SHO intake pics (Note that the V6 SHO, IIRC, has a valve and dedicated port for each runner in the head.) ...

cali92RS

Tight... never knew what SHO's looked like.

Oh, and Red Devil, I know we've had our differences, but I LOVE that quote in your sig from Ben Franklin. Its amazing...the more things change, the more they stay the same.

Vader

I know very well what the reflection of an SLO looks like...

As for the variable resonnant runner design, I'm just amazed that no one (including the tunnel-visioned, uni-dimensional, high-tech" auto manufacturers) has developed the obvious solution. Intake resonnance is based on impulsive generation, relefction, and the resultant pressure waves. Of the 36,000+ member we have here, at least a few hundred of you must have played, picked up, or at least SEEN a trombone over the years. I was always amazed at how much R&D Yamama and Dorf put into the 30-40' of tubing and valves for developing only two possible resonnant paths for induction, rather than have an infinitely variable system for all potential RPM and load ranges. All that while, GM used the non-resonnant LT1 intake to solve the same problem.

Worse yet, a non-resonnant plenum right over the valves feed by a SINGLE or only two variable length runners would be simpler and just as effecive in tuning intake resonnance for best charging. Yes, simple CAN actually be better, but SAE and JAI have apparently forgotten that. I suppose 60 years is a long time to remember that all the "high-tech" imports just don't stack up all that well to simple ingenuity and robustness.

IROC-Z28_CAMARO

iTrader: (4)

Don't the ford probes have something like this. It's called VRIS and opens at certain rpms to feed the engine more air, but are closed at rpm's under 4000 or somewhere around there to help low end. I think the controlled by a solenoid hooked up to the computer.

TexasB4C

iTrader: (1)

thats exactly what im talking about, Isuzu has the same thing in their V6's

Vader

Lots of engines have dual-runner intakes. It's actually pretty old technology that has been revived as a desperate attempt to eek adequate power out of weenie little displacements. Ford's 232V-6s have had this since at least 1996, even in Windstar minivans:

JPrevost

They have developed the "obvious solution." But the bean counters don't want anything to do with it. The Lt1 intake was probably used because of it's simplicity, high peak hp number, and profile height. Having a small plenum short runner single casted port injection intake and a high hp number can save you $$$ when you're producing as many as GM did. Not to mention the "lack of low and mid" range of the Lt1 was still more than the rival Mustang's DOHC 4.6L so why bother? The Lt1, other than the opti, is a great design but far from being optimized for total engine output.
Making an expensive intake for a 4 cylinder is easy, same with any inline engine. Doing it for a v8 and keeping it compact isn't easy. There would be compromises that just wouldn't outweigh the needed costs. From my perspective I think GM should be putting out high tech engines instead of throughing displacement around between models. The displacement game isn't as strong a selling point for people considering imports. They want something high-tech and efficient... something a large pushrod motor has to struggle with. The LS1 was great, it's high tech with the "if we don't need it, remove it." This created a light weight engine that doesn't waste power in rotating AND is lighter (lower cost of materials). It's a win win situation. The cars handle better, the shipping weight is lower, money saved all around compared to throughing 4 overhead cams onto a heavy 4 valve head.
GM's doing some things very right, others not so well, but I still have some faith because I have close conections inside that I talk to on a frequent basis.
Also, there's a think called a patent. GM hates paying people so they usually gobble them up by buying out the company first... Ferrari, Porsche, BMW, and Nissan (there are more but those stick in my head as being the first) have a lot of intake resonance patents and last time I checked those companies aren't exactly ready to sell out to GM. I could be wrong and tomorrow Ferrari get's owned by the General... by I hightly doubt it. Hence GM doing it their way, not somebody elses. Once the technology becomes cheap enough some fancy stuff will come out of GM but until then, just be happy they're still making v8's and perfecting them
I almost forgot the other major reason for not using inf-variable length runners/tuners... speed. An engine with some stought power can rev REALLY fast. You would need a really fast device to be adjusting the runner lengths as fast as the engine changes speed! Just one more reason it would cost too much for a v8 at this time.

Vader

Speed? Would 1,600 inches/minute of linear change be fast enough? It's happening daily with the same old, low-tech servoes like GM uses to control EGR valves. Machine tools that don't perform a rapid move at 800in/min are considered "slow" and out-of-date. And that's an entire machine axis, with saddles, turrets, tooling, etc. A tubular section of manifold could easily be moved much faster.

The more significant problem as I see it would be sealing the telescoping assembly. A close tolerance, polished pair of mating surfaces with flurocarbon seals would work well, tolerate the heat, fuel vapors, and some measure of dirt and contamination. A protective accordian bellows covering would take care of the rest of the contamination. Unfortunately, it wouldn't be pretty, just effective. TPI on the other hand looks appealing, but certainly isn't effective at a wide range of engine RPMs.

As for the LT1s lacking low-end torque, both of mine must be the exceptions. In a crank-to-crank comparison, I believe the LT1 would turn an L98 backward first (or rip the crank flange off trying).

JPrevost

You're right, they are considered slow and out-of-date... in a differen't industry. In the automotive industry the R&D is light years ahead of the current technology because unlike some industry, Automotive is held at an unheard of standard. It's so competative that demand for the best and nothing less without spending more than you did on a pair of home appliances is what is expected. Consumers want quiet but they want fast, they want fuel economy and they want fast, they want pretty and aggressive, dark and light, rear wheel drive and all wheel drive. It's absolutely amazing how much technology is passed down from aerospace into the automotive industry which then works the technology into perfection before passing it onto the millions of consumers and lastly to the home tech swavy. Sure you could use those expensive servo's but when it wouldn't increase sales and posibly put a dent in your profit margin why bother? Just sit on the patents like they're doing and wait for the demand to be high enough to ensure it's marketability. They do this with turbo's and new engines all the time. The only exception in recent history is the intro of the inline vortec 6 that preceded the i5 (that was pretty stupid). In anycase, the technology is there, it's just the bean counters that are slowing it down to maximize their profit margins while keeping sales up. It's a balancing act and the larger companies take much longer to react.

As for the Lt1 vs L98. If you took the TPI off of an L98 and installed it onto an Lt1 I'd expect to see the TPI doing the overpowering at low RPM. Comparing the L98 to an LT1 isn't right, just pick one long block and change just the intakes, the longer runners will resonate at a lower frequency and provide lower RPM torque. The proof is in the dyno charts. A good comparison would be an L98 with the Lt1 cam, stock TPI, and iron vortec heads compared to an iron headed L98 from the b-body's.

Red Devil

Differences probably mainly in style only. Not many like mine. But yes, it's amazing the cyclical nature of history. Too bad not many see, or acknowledge it.

Hey, enough of that metal head!! (Besides, SLOs are the non-SHO nomenclature the SHO community uses) Methinks you and I should have another chat about that certain intake project that was put on hold a few years back. I think I'm going to make a few to try out.